The invention relates to improvements in methods of and in apparatus for making brushes, brooms and the like (hereinafter called brushes). More particularly, the invention relates to improvements in methods of and in apparatus for making brushes containing bristles which are conveyed by a gaseous fluid.
German Pat. No. 845,933 to Schiffer et al. discloses a brush making apparatus wherein tufts of bristles are transported from a roll of convoluted bristles to the brush making station The making of tufts involves withdrawal of bristles from the roll and introduction of batches of bristles into through holes which are provided in a form. The leading ends of the bristles project beyond the respective holes so that they can be bonded to a brush body. The bristles are then severed at a distance from the brush body and the thus obtained free ends of bristles are trimmed. Such trimming often involves the formation of sharp edges which are likely to injure the gums of a user if the tufts are assembled with brush bodies to form toothbrushes. The same applies if the finished product is a hair brush, i.e., the sharp edges of free ends of the bristles are likely to injure or irritate the skin of the user. The situation is aggravated if the exposed ends or tips of the tufts are to be trimmed for the purpose of assuming a predetermined (e.g., conical or hemispherical) configuration which enables the free ends of the bristles to penetrate into spaces between the teeth of a user if the ultimate product is a toothbrush. Such shaping of the tips of tufts increases the danger of injury or irritation because the sharp edges of all or nearly all bristles in each tuft are free to come into contact with the gums in the mouth or with the skin on the head of the user of a toothbrush or hairbrush employing such tufts.
Attempts to avoid the aforediscussed drawbacks of conventional brushes involve a treatment of the free ends of bristles, namely a treatment which results in the making of rounded ends of bristles. However, such treatment is possible only if the tips of tufts of bristles are flat. Moreover, the treatment does not result in complete elimination of sharp edges.
Published German patent application No. 23 35 468 of Lewis discloses a method of and an apparatus for gathering bristles into tufts which are thereupon assembled with brush bodies. The bristles consist of a synthetic material and are withdrawn from a magazine by a tool having hollow tubular receptacles for batches of bristles. A drawback of this apparatus is that numerous bristles are deformed as a result of penetration of tubular receptacles into the magazine. Misalignment of bristles in the magazine prevents complete filling of receptacles with bristles so that the number of bristles in finished tufts departs from the optimum or desired number. In addition, the apparatus is rather complex and its output is unsatisfactory.
Published German patent application No. 34 05 001 of Bickel discloses a method of making brushes, brooms and like products. Bristles are assembled into tufts, and the bristles of each tuft are bonded to each other prior to being transported, by streams of compressed air, to the brush or broom making station. The pneumatic conveyor system employs conduits which can guide finished tufts (i.e., tufts of bristles which are already bonded to each other) but could not properly guide loose bristles. Loose bristles in a stream of compressed air or another compressed gaseous fluid are particularly likely to jam in arcuate sections of a conduit and at locations where they are caused to enter or leave the conduit. The making of finished tufts ahead of the pneumatic conveyor system involves losses in time and additional expenses because the bristles of each tuft must be welded to each other prior to transport to the brush or broom forming station where the tufts are affixed (e.g., welded) to the bodies of brushes or brooms. Frequent interruptions of pneumatic transport as a result of jamming of conveyed tufts also affects the output of the apparatus.
Published German patent application No. 28 08 966 of Lorenz discloses a brush making apparatus wherein the bristles are transported exclusively by mechanical means. The apparatus comprises means for maintaining bristles in vertical positions and employs an ejector for finished brushes.
U.S Pat. No. 3,230,015 to Iasillo discloses a brush making machine wherein the bristles are drawn from a magazine and are thereupon manipulated by mechanical means. The device which draws bristles from the magazine has recesses for bunches of bristles.
The apparatus which is disclosed in published German patent application No. 1 632 375 of Neubauer et al. also employs a tool having recesses for batches of bristles which are drawn from the bottom end of an upright magazine.
Published German patent application No. 36 16 976 of Blankschein discloses a form with sockets for batches of bristles. The shape of the bottom wall in each socket determines the configuration of the tip of the respective tuft.
German Pat. No. 27 31 762 to Zahoransky discloses a brush making apparatus wherein brushes are assembled in a number of successive stages. Each of those stations where the treatment of partially finished brushes or component parts of brushes takes up relatively long intervals of time is designed to accept two identical partly finished brushes or two identical component parts of brushes. The bristles are transported exclusively by mechanical means, the same as in each of the aforediscussed prior publications save for the published application of Bickel.
German Utility Model No. 1 769 825 of Greiner & Hausser discloses welding of bristles in batches of bristles to each other prior to partial insertion of the thus obtained tufts into and their welding to the body of a toothbrush. Portions of tufts can be inserted into blind bores or holes of the brush body, or are caused to extend all the way through the brush body to be secured to the latter by welding or by the application of a layer of hardenable material.
Published German patent application No. 25 39 417 of Hersche discloses a brush with replaceable bristles. To this end, batches of bristles are inserted into the through holes of a form which is located between a pusher plate and a heating plate. The pusher plate bears against the first ends of bristles and forces the second ends of such bristles against the heating plate which causes the adjacent portions of the bristles to melt. Molten material of the bristles is gathered into a thin substrate which is integral with the bristles of all batches so that the batches form tufts of bristles. The substrate can be secured to the periphery of a drum or to another holder of tufts. If the tufts are damaged or destroyed, the substrate is removed from the holder and is replaced with a substrate carrying a requisite number of fresh tufts. The substrate and its tufts are intended for use in plants or machines wherein the bristles are subjected to extensive wear and wherein it pays to replace the bristles while retaining all other parts of a cleaning, brushing, smoothing or like machine.